1. Field of the Invention
The present invention relates to a radio apparatus capable of quickly sending a distress signal in an emergency in which transmission of the distress signal is necessary without requiring a user to manipulate a power key even if a power unit is off.
2. Description of Related Art
Radio apparatuses for ships having a digital selective calling (DSC) function are also provided with a function of sending a distress signal in an emergency that the ship or a person(s) is in distress and requires rescue. Such radio apparatuses are equipped with a distress key for sending a distress signal, independently of the other switches.
The distress key is provided with a switch cover so that a distress signal is not sent by an inadvertent manipulation thereof, and the distress key itself or the switch cover is colored in red. Such radio apparatuses are configured in such a manner that the distress signal is not sent unless the distress key is manipulated continuously for three seconds. That is, a distress signal is sent only when a series of manipulations is made that the switch cover is opened and then the distress key is manipulated continuously for three seconds.
The distress signal includes MMSI (maritime mobile service identity) which is an ID code of the self station and is a 9-digit numeral, information indicating a position of the self station, time information, and a distress type. There are eleven distress types, that is, fire/explosion (“explosion”), “flooding”, “collision”, “grounding”, “capsizing”, “sinking”, incapability of steering the ship/adrift (“adrift”), “piracy”, abandoning of the ship (“abandoning”), man overboard (“MOB”), and “undesignated distress”.
The function of sending such a distress signal may be provided not only in radio apparatuses for ships but also in certain radio apparatuses for use on land.
JP-A-2002-111520 and JP-UM-A-05-009045 disclose radio apparatuses having a distress key for causing transmission of a distress signal of the above kind.
However, not only in the radio apparatuses disclosed in JP-A-2002-111520 and JP-UM-A-05-009045 but also in other conventional radio apparatuses having a function of sending a distress signal, it is assumed that the distress key is manipulated in a state that the radio apparatus is powered on. That is, no distress signal is sent if the distress key is manipulated in a state that the radio apparatus is powered off.
To send a distress signal from a state that the radio apparatus is powered off, it is necessary to perform a series of manipulations of turning the power on by manipulating the power key, confirming the powering-on, opening the switch cover, and continuing to manipulate the distress key for 3 sec. Because of setup of the radio apparatus, it takes about 5 sec from manipulation of the power key to the distress key's becoming manipulatable. Thus, in a state that the radio apparatus is powered off, a time lag of at least about 8 sec occurs from a start of manipulation of the power key to transmission of a distress signal.
As such, in conventional radio apparatuses, it is difficult to send a distress signal quickly in a state that they are powered off.